Additive for level nickel plating



United States Patent 3,219,559 ADDITIVE FOR LEVEL NICKEL PLATING Barnet D. Ostrow, 2181 Jellrey Drive, North Bellmore, N.Y., and Fred I. Nobel, 1587 Southern Drive, North Valley Stream, N.Y. No Drawing. Filed Apr. 23, 1958, Ser. No. 730,251 3 Claims. (Cl. 204-49) The present invention relates to the deposition of bright nickel deposits from acid baths, and more particularly to deposits of exceptional smoothness.

Prior nickel plating baths have resulted in relatively bright deposits, but in conjunction therewith certain difiiculties and disadvantages were encountered. In some, the rate of brightening was comparatively slow. Those baths which exhibited rapid brightening rates tended to produce brittle deposits. Numerous addition agents tended to produce low current density grayness, whereas others tended to produce skip plate.

It is among the objects of the present invention to overcome the difliculties and disadvantages inherent in the prior art and to provide a combination of additives to acid nickel plating baths which will have a high degree of leveling in the plating operation and over a wide range of current densities.

It is also among the objects of the invention to provide an additive to the bath Which will eliminate the tendency for the formation of gray deposits, and which will give bright deposits even in the low current density areas, the deposits being ductile.

It is further among the objects of the invention to provide an additive consisting of several constitutents which cooperate to give a synergistic result, providing deposits which are commercially desirable and acceptable.

In practicing the invention, there is provided a bath of nickel chloride or sulfate such as is common in the art. Atypical bath is as follows:

G./l. NisO .6H O 300 NisCl .6H O 45 Boric acid 45 Na lauryl sulfate .20

The additive is incorporated in the bath with a sulfonamide or a sulfonimide. There is further introduced with the sulfonamide or the sulfonimide, methylene-bis-naphthalene-sulfonic acid. These two constituents as the sole additives are insufiicient to produce all of the desired effectiveness, but the addition thereto of a polyamine or its reaction product with a vinyl compound or with an acetylenic compound of Patent No. 2,836,549, dated May 27, 1958, results in an additive which gives good leveling, ductile deposits and bright platings. Varying the proportions of the constitutents may enhance one physical property over another. For example, leveling may he still further improved with some reduction in covering power.

The sulfonamides and sulfonimides are well known compounds; they include the disulfonamides and disulfonimides. It is possible to use aliphatic or aromatic derivatives; however, the most commonly known compounds are those of benzene and naphthalene. They may have substituent groups which are inert in the bath and which do not adversely afiect the solubility of the compounds. They are used in the bath in amounts from about 0.2 grams per liter to saturation and the larger amounts are not detrimental to the operation.

3,219,559 Patented Nov. 23, 1965 The methylene-bis-naphthalene sulfonic acid has the following structural formula:

where n=1 to 50. In place of the naphthalene compound the corresponding benzene derivative is suitable. The amounts of these substances may vary Widely and as little as 0.05 gram per liter has been found sulficient to exert its beneficial effect. The method of making such compounds is found in the literature, for example, in the book by A. M. Schwartz and I. W. Perry entitled Surface Active Agents, published by Interscience Publications, Inc. (1949), page 119.

To produce the desired ductility and the desired characteristics of the deposit, a definite relationship between the sulfonamide or sulfonimide and the bis-sulfonic acid exists. Also, it should be noted that when the sulfonamide or sulfonimide is replaced by other well known primary brighteners such as benzene sulfonic 0r disulfonic acids, napthalene (mono, di or tri) sulfonic acids or their salts, no improved results occur. Deposits tend to be brittle and have a poor degree of leveling. Up to '50 grams per liter of the present compounds are usually used but higher amounts may be incorporated in the additive to the bath.

Polyamines having from 2 to 8 amino groups are suitable, as well as the reaction products thereof with various unsaturated compounds, whereby the double bond remains in the resulting product; they are ethylene and propylene polyamines. These compounds are used in extremely small amounts in the bath; from about 0.10 to 0.001 gram per liter have been found to be suflicient. Acetylenic polyamines are also suitable.

The following are a number of specific examples of additives to be introduced into the usual acid nickel plating baths, as illustrating the broad scope of the compounds and the proportions which have been found acceptable, the amounts being stated in grams per liter:

Example 1 O-benzoyl sulfonimide Na salt 1.0 Methylene-bis-naphthal'ene sulfonic acid 2.0

Vinyl acetate-tetraethylene pentamine 0.004 2-methyl-3-butyne-2-polyethyleneglycol 402 0.06

The bath has a pH of 2.5-4.0 and is operated at Example 2 O-benzoyl sulfonimide 1.0 Methylene-bisbenzene-sulfonic acid Na salt 8.0

Triethylenetetramine 0.003 2-rnethyl-3-butyne-2-polyethyleneglycol 402 0.06

The bath is operated under the conditions of Example 1.

Example 3 O-benzoyl sulfonimide 1.0 Methylene-bis-naphthalene-sulfonic acid Na salt 7.0 Vinyl acetate-tetraethylenepentamine 0.05 2-methyl-3-butyne-2-polyethyleneglycol 402 0.08

The bath is operated at 110 to F. at a pH of 2.5 to 4.0 without agitation. When air agitation is used the sodium lauryl sulfate is omitted.

3 Example 4 Dibenzene sulfonamide 1.5 Methylene-bis-naphthalene-sulfnic acid Na salt 2.0

Pentaethylenehexamine 0.003 1-propyne-3-polyethyleneglycol 232 0.03

A pH of 2.5 to 4.5 is maintained and plating is at 110 to 160 F.

Example 5 Benzene sulfonamide 0.25 O-benzoyl sulfonimide 0.80 Methylene-bis-naphthalene sulfonic acid Na salt 4.0

2-Cl-allylidine diacetate-tetraethylene-pentamine 0.005

Tetraethylenepentamine 0.005

1-propyne-3-polypropyleneglycol 232 0.08

Example 9 Saccharin (O-benzyl sulfonimide) 1.0

Methylene bis-naphthalene sulfonic acid Na salt 4.0

N,N,N ,N propargyl triethylenetetramine 0.01

2-methyl-3-butyne2-polyethyleneglycol 402 0.03

In all of the above examples, the conditions of the plating operations may be varied in accordance with usual practice and at the discretion of the operator with good results.

The improved result obtained by the invention is based on the use of a sulfonamide or a sulfonimide in conjunction with a sulfonic acid taken from the class consisting of methylene-bis-naphthalene and methylene-bis-benzene. Using this combination with a polyamine, either aliphatic or aromatic, will increase the leveling and smoothing characteristics of the bath and overcome the tendency for low current density grayness.

The brightness of the plating is readily controlled since the tolerance of the bath for added brighteners is increased. For example, the tendency toward grayness in the low current density areas is very marked with increased concentrations of polyamines or their reaction products, but With the introduction of the sulfonic acids the grayness is either eliminated or greatly reduced. The sulfonic acids when used in the bath, ordinarily do not overcome the brittleness of the deposits when brighteners are present which cause brittleness, but with the introduction of the sulfonimides or sulfonamides commercially acceptable ductile deposits are obtained.

What is claimed is:

1. In an acid nickel plating bath taken from the class consisting of chlorides and sulfates, the improvement which consists in an addition agent composed of a compound taken from the class consisting of sulfonarnides and sulfonimides in amounts of from about .2 g./l. to saturation together with a substance taken from the class consisting of rnethylene-bis-naphthalene and methylenebis-benzene sulfonic acids, in amounts of from about .05 to 50 g./ 1., said amounts being sufiicient to exert a leveling effect on the deposit of nickel.

2. A nickel plating bath according to claim 1 containing also a compound taken from the class consisting of polyamines having 2 to 8 amino groups, the alkyl radicals thereof having 2 to 3 carbon atoms, and the reaction products of said polyamines with unsaturated compounds, in amounts from about .001 to .10 g./l.

3. A nickel plating bath according to claim 1 containing also a compound taken from the class consisting of polyamines having 2 to 8 amino groups, the alkyl radicals thereof having 2 to 3 carbon atoms, and the reaction products of said polyamines with unsaturated compounds, in amounts from about .001 to .1 g./l.

References Cited by the Examiner UNITED STATES PATENTS 2,662,853 12/1953 Ellis 204-49 2,712,522 7/1955 Kardos et a1 204-49 2,782,155 2/1957 Du Rose et al. 204-94 2,849,353 8/1958 Kardos 204-49 2,882,208 4/1959 Becking et al. 204-49 FOREIGN PATENTS 542,292 11/1955 Belgium.

OTHER REFERENCES Schwartz et al.: Surface Active Agents (1949), page 119.

JOHN H. MACK, Primary Examiner. JOSEPH REBOLD, JOHN R. SPECK, Examiners, 

1. IN AN ACID NICKEL PLATING BATH TAKEN FROM THE CLASS CONSISTING OF CHLORIDES AND SULFATES, THE IMPROVEMENT WHICH CONSISTS IN AN ADDITION AGENT COMPOSED OF A COMPOUND TAKEN FROM THE CLASS CONSISTING OF SULFONAMIDES AND SULFONIMIDES IN AMOUNTS OF FROM ABOUT .2 G./L. TO SATURATION TOGETHER WITH A SUBSTANCE TAKEN FROM THE CLASS CONSISTING OF METHYLENE-BIS-NAPHTHALENE AND METHYLENEBIS-BENZENE SULFONIC ACIDS, IN AMOUNTS OF FROM ABOUT .05 TO 50 G./L., SAID AMOUNTS BEING SUFFICIENT TO EXERT A LEVELING EFFECT ON THE DEPOSIT OF NICKEL. 